Nodes - Added math expression node

Node - Fix visual script cable present event unregister

src/Artemis.VisualScripting/Nodes/Maths/CustomViewModels/MathExpressionNodeCustomViewModel.cs

@@ -0,0 +1,37 @@
+using System.ComponentModel;
+using Artemis.VisualScripting.Nodes.CustomViewModels;
+
+namespace Artemis.VisualScripting.Nodes.Maths.CustomViewModels
+{
+    public class MathExpressionNodeCustomViewModel : CustomNodeViewModel
+    {
+        private readonly MathExpressionNode _node;
+
+        public MathExpressionNodeCustomViewModel(MathExpressionNode node) : base(node)
+        {
+            _node = node;
+        }
+
+        public string Input
+        {
+            get => (string)_node.Storage;
+            set => _node.Storage = value;
+        }
+
+        public override void OnActivate()
+        {
+            _node.PropertyChanged += NodeOnPropertyChanged;
+        }
+
+        public override void OnDeactivate()
+        {
+            _node.PropertyChanged -= NodeOnPropertyChanged;
+        }
+
+        private void NodeOnPropertyChanged(object sender, PropertyChangedEventArgs e)
+        {
+            if (e.PropertyName == nameof(Node.Storage))
+                OnPropertyChanged(nameof(Input));
+        }
+    }
+}

src/Artemis.VisualScripting/Nodes/Maths/CustomViews/MathExpressionNodeCustomView.xaml

@@ -0,0 +1,12 @@
+<UserControl x:Class="Artemis.VisualScripting.Nodes.Maths.CustomViews.MathExpressionNodeCustomView"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
+             xmlns:local="clr-namespace:Artemis.VisualScripting.Nodes.Maths.CustomViews"
+             mc:Ignorable="d" 
+             d:DesignHeight="450" d:DesignWidth="800">
+    <TextBox VerticalAlignment="Bottom"
+             HorizontalAlignment="Stretch"
+             Text="{Binding Input}" />
+</UserControl>

src/Artemis.VisualScripting/Nodes/Maths/ExpressionNode.cs

@@ -0,0 +1,112 @@
+using System;
+using System.Linq;
+using Artemis.Core;
+using Artemis.VisualScripting.Nodes.Maths.CustomViewModels;
+using NoStringEvaluating.Contract;
+using NoStringEvaluating.Contract.Variables;
+using NoStringEvaluating.Models.Values;
+
+namespace Artemis.VisualScripting.Nodes.Maths
+{
+    [Node("Math Expression", "Outputs the result of a math expression.", "Math", OutputType = typeof(int))]
+    public class MathExpressionNode : Node<MathExpressionNodeCustomViewModel>
+    {
+        private readonly INoStringEvaluator _evaluator;
+        private readonly PinsVariablesContainer _variables;
+
+        #region Constructors
+        public MathExpressionNode(INoStringEvaluator evaluator)
+            : base("Math Expression", "Outputs the result of a math expression.")
+        {
+            _evaluator = evaluator;
+            Output = CreateOutputPin<float>();
+            Values = CreateInputPinCollection<float>("Values", 2);
+            Values.PinAdded += (_, _) => SetPinNames();
+            Values.PinRemoved += (_, _) => SetPinNames();
+            _variables = new PinsVariablesContainer(Values);
+            
+            SetPinNames();
+        }
+
+        #endregion
+
+        #region Properties & Fields
+
+        public OutputPin<float> Output { get; }
+        public InputPinCollection<float> Values { get; }
+
+        #endregion
+
+        #region Methods
+
+        public override void Evaluate()
+        {
+            if (Storage is string formula) 
+                Output.Value = (float) _evaluator.CalcNumber(formula, _variables);
+        }
+
+        private void SetPinNames()
+        {
+            int index = 1;
+            foreach (IPin value in Values)
+            {
+                value.Name = ExcelColumnFromNumber(index).ToLower();
+                index++;
+            }
+        }
+
+        public static string ExcelColumnFromNumber(int column)
+        {
+            string columnString = "";
+            decimal columnNumber = column;
+            while (columnNumber > 0)
+            {
+                decimal currentLetterNumber = (columnNumber - 1) % 26;
+                char currentLetter = (char) (currentLetterNumber + 65);
+                columnString = currentLetter + columnString;
+                columnNumber = (columnNumber - (currentLetterNumber + 1)) / 26;
+            }
+
+            return columnString;
+        }
+
+        #endregion
+    }
+
+    public class PinsVariablesContainer : IVariablesContainer
+    {
+        private readonly InputPinCollection<float> _values;
+
+        public PinsVariablesContainer(InputPinCollection<float> values)
+        {
+            _values = values;
+        }
+
+        #region Implementation of IVariablesContainer
+
+        /// <inheritdoc />
+        public IVariable AddOrUpdate(string name, double value)
+        {
+            throw new NotImplementedException();
+        }
+
+        /// <inheritdoc />
+        public EvaluatorValue GetValue(string name)
+        {
+            IPin pin = _values.FirstOrDefault(v => v.Name == name);
+            return pin == null ? new EvaluatorValue(0) : new EvaluatorValue((double) pin.PinValue);
+        }
+
+        /// <inheritdoc />
+        public bool TryGetValue(string name, out EvaluatorValue value)
+        {
+            IPin pin = _values.FirstOrDefault(v => v.Name == name);
+            double unboxed = (float) pin.PinValue;
+            value = pin == null ? new EvaluatorValue(0) : new EvaluatorValue(unboxed);
+
+            return pin != null;
+        }
+
+        #endregion
+    }
+}